I haven't found the means to do this yet, I do know you can open ESRI's ArcExplorer 2 with from Excel VBA and have it open a particular project file, shapefile, or server (w/query parameter) -- but to do this you use a particular object that happens to be accessible for doing such a thing. I'll poke around for anything similar for Google Earth -- but in any case you should get to know the KML file structure, what you'd probably end up doing is havin Excel generate a KML file to pass over to Google Earth for opening. I'll try and note to get back to this thread if I have success with it.